**Answer:**

3

**Step-by-step explanation:**

**Answer:**

(x,y) -> (-y,x), second option.

**Step-by-step explanation:**

**Rotation of 90 degrees about the origin:**

The rule for a rotation of a point (x,y) 90 degrees about the origin is given by:

(x,y) -> (-y,x)

This is that the question asks, and so, this is the answer, which is the second option.

**Answer:**

<em>The last choice is correct</em>

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**Step-by-step explanation:**

<u>Least Common Multiple (LCM)</u>

To find the LCM we can follow this procedure:

List the prime factors of each monomial.

Multiply each factor the greatest number of times it occurs in either factor.

We have two monomials:

The prime factors of the first monomial are:

The prime factors of the second monomial are:

LCM = Multiply

These are all the factors the greatest number of times they occur.

Operating:

The last choice is correct

hope this answer helps you dear...take care!